<h2>DESCRIPTION</h2>

<em>i.tasscap</em> calculates Tasseled Cap (Kauth Thomas, TC) transformation
for Landsat TM data (TM4, TM5, ETM7), MODIS and Sentinel-2 data.

The tasseled cap transformation is effectively a compression method to
reduce multiple spectral data into a few bands. The method was originally
developed for understanding important phenomena of crop development in
spectral space (Kauth and Thomas, 1976).
<p>
Tasseled cap coefficients for Landsat 7 ETM+ are at-satellite reflectance
values (C. Huang et al., 2001), the conversion can be achieved with
<em>i.landsat.toar</em>.
<p>
The following tasseled cap components are generated:

<ul>
<li> tasscap.1: corresponds to brightness,
<li> tasscap.2: corresponds to greenness,
<li> tasscap.3: corresponds to wetness,
<li> tasscap.4: corresponds to atmospheric haze (only selected sensors: Landsat 5,7,8).
</ul>


<h2>EXAMPLE</h2>

Calculation of TC maps from North Carolina Landsat 7 ETM scene:

<div class="code"><pre>
# See manual page of i.landsat.toar for pre-processing

g.region raster=lsat7_2002_toar.1 -p

i.tasscap sensor=landsat7_etm \
  input=lsat7_2002_toar.1,lsat7_2002_toar.2,lsat7_2002_toar.3,lsat7_2002_toar.4,lsat7_2002_toar.5,lsat7_2002_toar.7 \
  output=lsat7_2002_tasscap
</pre></div>

Results:

<p>
<center>
  <table border=1>
  <tr>
    <td align=center>
      &nbsp;<img src="i_tasscap_brightness.jpg" alt="'Brightness' Tasseled Cap component 1">
      <br>
      <font size="-1">
      <i>'Brightness' Tasseled Cap component 1</i>
      </font>
    </td>
    <td align=center>
      &nbsp;<img src="i_tasscap_greenness.jpg" alt="'Greenness' Tasseled Cap component 2">
      <br>
      <font size="-1">
      <i>'Greenness' Tasseled Cap component 2</i>
      </font>
    </td>
  </tr>
  <tr>
    <td align=center>
      &nbsp;<img src="i_tasscap_wetness.jpg" alt="'Wetness' Tasseled Cap component 3">
      <br>
      <font size="-1">
      <i>'Wetness' Tasseled Cap component 3</i>
      </font>
    </td>
    <td align=center>
      &nbsp;<img src="i_tasscap_haze.jpg" alt="'Atmospheric haze' Tasseled Cap component 4">
      <br>
      <font size="-1">
      <i>'Atmospheric haze' Tasseled Cap component 4</i>
      </font>
    </td>
  </tr>
  </table>
</center>
<br>


<h2>REFERENCES</h2>

<ul>
<li>LANDSAT-4/LANDSAT-5: TC-factor changed to CRIST et al. 1986,
                      Proc. IGARSS 1986, p.1467</li>
<li>Crist, E. P., 1985, A TM tasseled cap equivalent transformation for reflectance
    factor data, Remote Sensing of Environment, 17: 301-306.</li>
<li>LANDSAT-7: TASSCAP factors cited from:
  DERIVATION OF A TASSELED CAP TRANSFORMATION BASED ON LANDSAT 7 AT-SATELLITE REFLECTANCE.
  Chengquan Huang, Bruce Wylie, Limin Yang, Collin Homer and Gregory Zylstra Raytheon ITSS, 
  USGS EROS Data Center Sioux Falls, SD 57198, USA (http://landcover.usgs.gov/pdf/tasseled.pdf).
  This is published as well in INT. J. OF RS, 2002, VOL 23, NO. 8, 1741-1748.</li>
<li> MODIS Tasseled Cap coefficients - Ref: Lobser &amp; Cohen (2007). MODIS tasseled cap:
 land cover characteristics expressed through transformed MODIS data.
 International Journal of Remote Sensing, Volume 28(22), Table 3</li>
<li> Sentinel-2 Tasseled Cap coefficients - Ref: Nedkov, R. (2017). Orthogonal transformation
  of segmented images from the satellite Sentinel-2.
  Comptes rendus de l'Acad&eacute;mie bulgare des sciences, 70:687-692.</li>
<li>Yarbrough, L., Navulur, R., 2014, Presentation of the Kauth-Thomas transform
  for WorldView-2 reflectance data. Remote Sensing Letters. 5. DOI: 10.1080/2150704X.2014.885148.</li>
</ul>

<h2>SEE ALSO</h2>

<em>
<a href="i.albedo.html">i.albedo</a>,
<a href="i.atcorr.html">i.atcorr</a>,
<a href="i.landsat.toar.html">i.landsat.toar</a>,
<a href="i.vi.html">i.vi</a>
</em>

<h2>AUTHORS</h2>

Dr. Agustin Lobo, original script, 1997
<p>
Markus Neteler, ITC-irst, 2001
<p>
Converted to Python by Glynn Clements
<p>
Code improvements by Leonardo Perathoner
<p>
Sentinel-2 support by Veronica Andreo
<p>
Worldview-2 support by Markus Neteler

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